Electrolytic process for the production of metallic titanium from aqueous solution of titanium compounds



United rates My invention relates to a process for the production ofmetallic titanium, and more particularly to an electrolytic process forthe production of metallic titanium.

Metallic titanium is now produced by a dry method. There have been mademany attempts to obtain metallic titanium by a wet method but none hassucceeded. Thus, up to the present, production of metallic titanium byelectrolysis of an aqueous solution of its compound has been consideredas a very difiicult problem.

I have now devised a process to produce pure metallic titanium byelectrolysis of an aqueous solution of titanium compounds economicallyat low cost. My novel process for the production of metallic titaniumfrom an aqueous solution of titanium compounds comprises a water-solubletitanium compound in which titanium which has a valency of two or threeis employed as the starting material. In the case where a titaniumcompound in which titanium has a valency of three is employed thecompound is converted into a titanium compound in which titanium has avalency of two by reduction by means of a reducing metal or agent, or byelectrolytic reduction, or by the combination of said two reductionmethods, and the titanium compound in which titanium has a valency oftwo thus converted from a titanium compound in which titanium has avalency of three or a titanium compound in which titanium has a valencyof two in itself is made alkaline such that a sufficient reducingcondition will exist in the electrolyte solution during the electrolysisoperation, and it is then electrolyzed.

As the starting material for my process water-soluble titanium in whichtitanium has a valency of two or three may be used. When a titaniumcompound in which the valency of titanium is three is employed, it ispreferable to use such a titanium compound which can easily be convertedinto a titanium compound in which the valency of titanium is two, forexample, halides, complex salts, etc.

When a titanium compound in which titanium has a valency of three isemployed, the compound is converted into a titanium compound in whichtitanium has a valency of two by means of a reducing metal or agent orby electrolytic reduction or by the combination of said two reductionmethods.

Titanium compounds in which titanium has a valency of three have theadvantage that they are more stable and more easily obtainable. However,when a titanium compound in which titanium has a valency of three isemployed, the compound must be converted into a titanium compound havinga valency of two before electrolysis by employing a reducing metal oragent or by electrolytic reduction or by the combination of said tworeduction methods. For example, the reduction can be accomplished by theuse of sponge titanium, or formaldehyde, or hydrazine hydrate, orpyrogallic acid, or by combinations of two of these reducing agents. Itmay be also accomplished by electrolytic reduction either by itself orin combination with the use of one of the aforementioned reducingagents.

An aqueous solution of a water-soluble titanium compound in whichtitanium has a valency of two, which 3,074,860 Patented Jan. 22, 1963may be a titanium compound in which titanium has a valency of two initself, or a titanium compound in which titanium has a valency of twowhich has been converted from a titanium compound in which titanium hasa valency of three, must be adjusted so as to be alkaline. The aqueousalkaline solution is then subjected to electrolysis. When theelectrolysis is carried out with the solution alkaline such that asufficient reducing condition exists in the electrolyte solutionmetallic titanium having a high purity is deposited on the cathode.

The reason why electrolytic production of metallic titanium which hadbeen very difficult has been made possible by my process may beexplained by the fact that, according to my process, a titanium compoundin Which titanium has a valency of two is employed and a. suflicientreducing condition exists in the electrolyte solution during theelectrolysis so that the oxidation of the titanium compound in whichtitanium has a valency of two in the electrolyte to a titanium compoundinwhich titanium has a valency of three is prevented and, also, theoxidation of metallic titanium deposited on the cathode is prevented.The fact that the hydrogen ion concentration of the electrolyte solutionis in the alkaline range produces the favorable result of bringing thepotential at which hydrogen is evolved and the potential at whichmetallic titanium is deposited close to each other. By the combinedettects of above, pure metallic titanium is deposited on the cathodewhile hydrogen is being evolved on it. Thus, according to the process ofmy invention, metallic titanium is deposited on the cathode undersimilar conditions which prevail in the electrolytic production ofmanganese.

The process of my invention will be more clearly understood from theexamples set forth below in which Examples I to VI illustrate thepreparation of electrolyte solution of titanium compound in whichtitanium has a valency of two and Example VIE illustrates the elec-.trolysis operation. It will be understood that these examples are onlyfor the purpose of illustration and my invention is in no way limited tothe examples.

Example I An aqueous solution suitable for the electrolytic productionof metallic titanium was prepared by dissolving 35 grams of titaniumdichloride in 300 cc. of commercial aqueous formaldehyde solution,adding to the solution 10 grams of pyrogallic acid and then aqueousammonia or caustic alkali to make the solution alkaline.

Example 11 To 300 cc. of an alcoholic solution of titanium trichloridewere added 300 cc. of commercial aqueous formaldehyde solution and then15 grams of pulverized sponge titanium. The mixture was heated at about50 C. When the reduction was completed, the mixture was cooled and 10grams of pyrogalli-c acid were added. Then, aqueous ammonia was added tomake the solution alkaline. The resultant solution was used as theelectrolyte solution for the production of metallic titanium accordingto my process.

Example 111 To 300 cc. of an aqueous solution of titanium borofluoride(titanium content 20.28 grams/liter) 50 cc. of thioglycollic acid wereadded and the resultant solution was electrolytically reduced using acarbon anode. When the reduction had proceeded to a point at which thesolution turned to brown in color, the electrolysis was stopped. 10grams of pyrogallic acid were added and then the solution was madealkaline by the addition of aqueous ammonia. The resultant solution wasused as the electrolyte solution for the production of metallic titaniumaccording to my process.

Example IV To 300 cc. of a solution of titanium trihydroxide incommercial aqueous formaldehyde solution (titanium content 18.73grams/liter) grams of pyrogallic acid were added, and the resultantsolution was subjected to the electrolytic reduction in the same manneras described in Example III. The resultant solution was made alkaline bythe addition of aqueous ammonia. The solution was used as theelectrolyte solution for the production of metallic titanium accordingto my process.

Example V To 300 cc. of a solution of titanium triethylate in ethylalcohol (titanium content 17.94 grams/liter) 50 cc. of hydrazine hydrate(80%) were added and the solution was made alkaline with aqueousammonia. The resultant solution was used as the electrolyte solution forthe production of metallic titanium according to my process.

Example VI To 300 cc. of a solution of titanium trihydroxide incommercial aqueous formaldehyde solution (titanium content 18.73grams/liter) 50 cc. of hydrazine hydrate (80%) were added and thesolution was made alkaline with aqueous ammonia. The resultant solutionwas used as the electrolyte solution for the production of metallictitanium according to my process.

Example VII To 300 cc. of an alcoholic solution of titanium trifluoride(titanium content 19.67 grams/liter) 50 cc. of hydrazine hydrate (80%)were added and the solution was made alkaline with aqueous ammonia.

Hydrogen ion concentration of the resultant solution was adjusted to apH of 8 to 12, such that a sutficient reducing condition existed in theelectrolyte solution for the electrolytic deposition of metallictitanium, and the solution was electrolyzed. A titanium deposit having abeautiful metallic luster was obtained on the cathode.

Conditions of electrolysis employed were as follows:

Cell material Glass.

Volume of electrolyte solution" 2.5 liters.

Electrode material Anode: carbon; cathode: pure copper plate.

Current density 7 amp. per square decimeter.

Cell voltage 1.3 volts.

Distance between the electrodes- 85 mm.

Temperature of the electrolyte solution 18 C.

Conditions in the electroylte solution Always reducing. Rate-of titaniumdeposition 860 mg. per hour.

As will be seen from above, according to the process of my invention itis possible to obtain pure metallic titanium easily and economically. Myprocess is particularly suitable for titanium plating since titanium ofhighest purity is deposited in a dense structure.

I claim:

1. .An electrolytic process for the production of metallic titanium fromaqueous solution of titanium compounds which comprises preparing analkaline, aqueous solution of a titanium compound in which titanium hasa valency of two and in which reducing conditions exist, and subjectingthe solution to electrolysis while reducing conditions exist in theelectrolyte solution.

2. A process as described in claim 1 wherein the titanium compound istitanium dichloride.

3. An electrolytic process for the production of metallic titanium fromaqueous solution of titanium compounds which comprises preparing anaqueous solution of a titanium compound in which titanium has a valencyof three, converting the titanium compound into a titanium compound inwhich titanium has a valency of two by reduction, adjusting the aqueoussolution of titanium compound in which titanium has a valency of twothus converted from the titanium compound in which titanium has avalency of three to alkaline condition so that reducing conditions existin the solution, and subjecting the alkaline, aqueous solution toelectrolysis while reducing conditions exist in the electrolyte solutionduring the electrolysis operation.

4. A process as described in claim 3 wherein the titinium compound inwhich titanium has a valency of three is reduced by means of pulverized,sponge titanium.

5. A process as described in claim 3 wherein the titanium compound inwhich titanium has a valency of three is reduced by means offormaldehyde.

6. A process as described in cailm 3 wherein the tanium compound inwhich titanium has a valency three is reduced by means of hydrazinehydrate.

7. A process as described in claim 3 wherein the tanium compound inwhich titanium has a valency three is reduced by means of pyrogallicacid.

8. A process as described in claim 3 wherein the tanium compound inwhich titanium has a valency of three is reduced by means ofelectrolytic reduction of an aqueous solution of the titanium compoundto which a reducing acid has been added.

9. A process as described in claim 3 wherein the titanium compound inwhich titanium has a valency of three is titanium trifluoride.

10. A process as described in claim 3 wherein the titanium compound inwhich titanium has a valency of three is titanium borofluoride.

11. A process as described in claim 3 wherein the ti tanium compound inwhich titanium has a valency of three is titanium trihydroxide.

12. A process as described in claim 3 wherein the titanium compound inwhich titanium has a valency of three is titanium triethylate.

13. An electrolytic process for the production of metallic titanium fromaqueous solution of titanium compounds which comprises preparing anaqueous solution of titanium compound in which titanium has a valency oftwo, adjusting the pH of the aqueous solution of titanium compound to asuificiently alkaline value to bring the potential at which hydrogen isevolved and the potential at which titanium is deposited close to eachother so that metallic titanium is deposited on the cathode whilehydrogen is being evolved on it during the electrolysis and so thatreducing conditions exist in the solution, and electrolyzing theso-adjusted aqueous solution of titanium compound in which titanium hasa valency of two while reducing conditions exist in the electrolytesolution.

14. A process as claimed in claim 3 in which the reduction is carriedout by dissolving the trivalent titanium compound in an aqueousformaldehyde solution and then adding pyrogallic acid.

15. A process as claimed in claim 3 in which the reduction is carriedout by dissolving the trivalent titanium compound in aqueousformaldehyde and then adding pulverized sponge titanium and heating themixture.

16. A process as claimed in claim 3 in which the reduction is carriedout by adding to an aqueous solution of the trivalent titanium compoundthioglycollic acid, and then subjecting the resulting solution toelectrolysis.

17. A process as claimed in claim 3 in which the reduction is carriedout by adding to an aqueous solution of the trivalent titanium compoundpyrogallic acid, and then subjecting the resulting solution toelectrolysis.

18. The process as claimed in claim 3 in which the reduction is carriedout by adding to an ethyl alcohol solution of the trivalent titaniumcompound hydrazine hydrate.

19. A process as claimed in claim 3 in which the retiof tiof 5 ductionis carried out by adding hydrazine hydrate to a formaldehyde solution ofthe trivalent titanium compound.

References Cited in the file of this patent UNITED STATES PATENTS1,113,546 Dekker Oct. 13, 1919 2,833,706 Wainer May 6, 1958 2,881,055Dean Apr. 7, 1959 6 FOREIGN PATENTS OTHER REFERENCES Breton, E. J.:Electrodeposition of Titanium From Aqueous Systems, Wright AirDevelopment Center Technical Report 52-232, Dayton, December 1952, pages1-75.

1. AN ELECTROLYTIC PROCESS FOR THE PRODUCTION OF METALLIC TITANIUMAQUEOUS SOLUTION OF TITANIUM COMPOUNDS WHICH COMPRISES PREPARING ANALKALINE, AQUEOUS SOULTION OF A TITANIUM COMPOUND IN WHICH TITANIUM HASA VALENCY IF TWO AND IN WHICH REDUCING CONDITION EXISTS, AND SUBJECTINGTHE SOULTION TO ELECTROLYSIS WHILE REDUCING CONDITIONS EXIST IN THEELECTROLYTE SOULTION.